[cfe-commits] [PATCH] Add a warning for a function declaration that shadows a tag type

[Manuel Klimek]

+  "function %0 shadows %1 %0; uses of %1 %0 will require an '%1' tag">,

I'd use 'a' or a selector for enum.

+void Sema::ActOnStartFunctionDeclarator(Scope* S, Declarator& D) {

* and & to the variable.

+      if (TagDecl *TD = dyn_cast_or_null<TagDecl>(*I)) {

I've searched, but couldn't find why *I would ever be NULL here...

Cheers,
/Manuel

On Thu, Apr 12, 2012 at 10:05 PM, Kaelyn Uhrain <rikka at google.com> wrote:
> Ping.
>
> Unless I hear something, I'll go ahead and commit the patch tomorrow
> morning.
>
>
> On Wed, Apr 11, 2012 at 1:44 PM, Kaelyn Uhrain <rikka at google.com> wrote:
>>
>> Hi,
>>
>> This warning is to help make code like:
>>
>> class Foo {
>>  public:
>>   enum Bar { X, Y };
>>   void SetBar(Bar bar);  // Setter
>>   Bar Bar()  // Getter
>>  private:
>>   Bar bar_;
>> };
>> void Foo::SetBar(Bar bar) { bar_ = bar; }
>> Foo::Bar Foo::Bar() { return bar_; }
>>
>>
>> be a bit easier to diagnose. Currently clang spits out a bunch of errors
>> without any real indication of what went wrong (the first error is the only
>> remotely helpful one, but it doesn't give any reason why an 'enum' tag has
>> to be added):
>>
>> tmp.cc:7:3: error: must use 'enum' tag to refer to type 'Bar' in this
>> scope
>>   Bar bar_;
>>   ^
>>   enum
>> tmp.cc:9:11: error: variable has incomplete type 'void'
>> void Foo::SetBar(Bar bar) { bar_ = bar; }
>>           ^
>> tmp.cc:9:18: error: use of undeclared identifier 'Bar'
>> void Foo::SetBar(Bar bar) { bar_ = bar; }
>>                  ^
>> tmp.cc:9:26: error: expected ';' after top level declarator
>> void Foo::SetBar(Bar bar) { bar_ = bar; }
>>                          ^
>>                          ;
>> 4 errors generated.
>>
>>
>> With the patch, clang emits a warning before that cascade of errors:
>>
>> tmp.cc:5:7: warning: function 'Bar' shadows enum 'Bar'; uses of enum 'Bar'
>> will require an 'enum'
>>       tag [-Wshadow]
>>   Bar Bar();  // Getter
>>       ^
>> tmp.cc:3:3: note: 'Bar' declared here
>>   enum Bar { X, Y };
>>   ^
>> tmp.cc:7:3: error: must use 'enum' tag to refer to type 'Bar' in this
>> scope
>> <and the rest of the messages from the first output example>
>>
>>
>> I'm sending the patch for pre-commit review both because I'm uncertain
>> about the wording of the wording, and primarily because I'm not sure that
>> modifying Sema::ActOnStartFunctionDeclarator is the right place for the
>> check (though it was the best candidate I could find).
>>
>> I'd also like to clean up the errors (in a separate patch) but the errors
>> seem to involve a lot of interactions between the parser and sema and may
>> take a while for me to figure out how to get things to work right. ;)
>>
>> Cheers,
>> Kaelyn
>
>
>
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